Uninterrupted arc chute venteng path for jump gap and runner



W. A. CARTER C CHUTE VENTING PATH GAP AND RUNNER March 12, 1963 5 Sheets-Sheet l UNINTERRUPTED AR FOR JUMP vFilec l Dec. 19., 1960 IN VEN TOR. W/A 1 MM A. 0419M! BY I 0674 9. 50%, 54:54 fans bFF March 12, 1963 Filed Dec.

w. A. CARTER 3,081,389 UNINTERRUPTED ARC CHUTE VENTING PATH FOR JUMP GAP AND RUNNER 3 Sheets-Sheet 2 26 INVENTOR. O 40/14/417 4. 0,4122

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March 12, 1963 w. A. CARTER 3,081,389

UNINTERRUPTED ARC CHUTE VENTING PATH FOR JUMP GAP AND RUNNER Filed Dec. 19, 1960 3 Sheets-Sheet 3 B Y @szmzavm 6182 4476 ff'oFia-w United States Patent Ofiice 3,031,389 UNINTERRUPTED ARC CHUTE VENTlNG PATH FOR JUMP GAP AND RUNNER William A. Carter, Devon, Pa, assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Dec. 19, 1960, Ser. No. 76,544 7 Claims. (Cl. 200-144) This invention relates to circuit breakers and more particularly to a circuit breaker arc chute having a novel passage permitting rapid removal of ionized gases in the region of the breaker contacts to the top of said are chute.

During the tripping operation of circuit breakers, an electric arc forms between the separating contacts. The air in the region of the contacts becomes heated and ionized due to the action of the arc. The close spacing of the arc plates prevents the heated gases from rising rapidly to the top of the arc chute. A large amount of the heated gases is forced to remain in the region between the lower edges of the arc plates and the separating contacts. At this time the arc is transferred from the separating contacts to the ar-c'runners under the influence of intense magnetic blow-off efiect and the upward moving heated gases. The are upon transferring to the arc burners energizes the magnetic blow-out means of the arc chute which urges the are deeply into the arc chute. The voltage drop developed by the blow-out coil appears across the jump gap which is located between the upper terminal of the breaker and the lower edge of the rear arc runner. A large amount of the ionized gases which are collecting below the arc plates gathers in the region of the jump gap. The ionized gases in the region of the jump gap coupled with the voltage drop across the gap create an environment which is conductive to striking.

an arc across the jump gap. Once this restrike occurs the arc across the jump gap de-energizes the blow-out coil. The main are drawn between the arc runners is no longer under the influence of the magnetic field generated by the blow out coil and moves much slower through the arc chute, thus seriously affecting the efficiency of the arc chute,

. As the main are moves upward along the arc runners, the ionized gases which remain in the region below the arc plates cause the arc to transfer to the lower edges of the arc runners since these inward sloping edges are closer together than the vertical portions of the are runners. It is apparent, therefore, that the ionized gases which collect beneath the arc plates produce an environment which can re-ignite the main arc in the immediate region of the separating contacts. Such operation defeats the primary function of an arc chute which is rapid extinguishment of an arc.

One solution of the problem is to space the arc plates wider apart to permit more rapid upward movement of the ionized gases. This solution creates a disadvantage in that the use of a lesser number of arc plates does not present as tortuous a path for the arc. Furthermore, the increase in ionized gases above the arc chute produces an environment which is conducive to ignition of the power are in the region above the arc plates and outside of the interrupting chamber which is completely beyond the control of the arc chute.

My invention provides for the rapid removal of the ionized gases from the region beneath the arc plates without reducing the number of arc plates. One or both of the arc runners in my novel are chute are arranged to provide a passage which communicates directly between the region below the arc plates and the top of the arc chute. The passage is substantially as long as the arc chute, causing the existing gases passing therethrough to be adequately cooled and deionized before leaving the 3,081,389 Patented Mar. 12, 1963 top of the arc chute. This prevents an are from forming between the arc runners above the arc plates.

The are runner has a novel configuration which permits ionized gases formed in the region of the arc to move to the lower opening of the passage unimpeded by any obstructions. Guide plates are provided to guide the movement of ionized gases through the jump gap directly to the lower opening of the passage. A V-shaped slot is provided at the lower end of the arc runner which further aids in the movement of ionized gases towards the lower opening of the passage.

Since the novel arrangement of my arc chute provides for such rapid removal of ionized gases collecting beneath the arc plates, the arc plates may be positioned closer to the separating contacts Without any danger of the arc restriking between the inward sloping portion of the arc runners. This permits the use of a shorter arc chute housing, thus reducing the distance the arc mus-t travel before striking the ceramic plates which shortens the arcing time and improves efiiciency.

It is, therefore, an object of my invention to provide a novel are chute for a circuit breaker which is so arranged to permit rapid removal of ionized gases generated during the tripping operation of the breaker.

Another object of my invention is to provide a novel are chute for a circuit breaker which is so arranged to provide for rapid extinguishment of an arc.

Another object of my invention is to provide an arc chute having passage for rapidly removing ionized gases generated in the arc chute.

Still another object of my invention is to provide an arc chute having a novel are runner which is adapted to permit rapid removal of ionized gases formed during the tripping operation.

Another object of my invention is to provide an arc chute which is so arranged to guide ionized gases formed during the tripping operation towards a passage wherein the gases are cooled and deionized.

These and other objects and advantages of the invention will become apparent upon consideration of the following detailed description of one embodiment thereof when taken in connection with the appended drawings wherein:

. FIGURE 1 is a perspective view of a circuit breaker embody-ing my novel are chute wherein the circuit breaker is shown in its closed position.

FIGURE 2 is a side plan view of a circuit breaker corresponding to FIGURE 1 in which the contacts of the circuit breaker are shown in their open position.

FIGURE 3 is a side plan view of the circuit breaker of FIGURE 1 with the breaker contacts in the engaged position.

Referring now to the drawings, FIGURE 1 shows a circuit breaker designated generally as numeral 10 which is connected to the leads 11 and 12 of the circuit to be protected by upper and lower terminals 13 and 14, respectively. Terminals 13 and 14 are arranged in any suitable manner to be easily removed from circuit leads 13 and 14 for inspection or replacement purposes. The opposite end of upper terminal 13 is connected to conductive head 15 which is fixedly mounted to the breaker support (not shown). Main 16 and arcing 17 contacts are pivotally mounted to conductive head 15. Contacts 16 and 17 cooperate with contacts 18 and 19, respectively, contacts 18 and 19 being fixedly mounted to bridge 20. Bridge 20 is pivotally mounted at 22 to stationary block 23 which provides a conductive path between bridge 20 and lower terminal 14. Bridge 21 is operable between an open and a closed position under control of pushrod 26 which is pivotally mounted at 25 to branch .arm 24 which is fixedly mounted to bridge 21.

Positioned above the cooperating contacts 16 through 19 is my novel are chute 30. The housing 31 of arc chute 30 has been partially removed to expose the internal arrangement of the arc chute 3% Front 33 and a rear 32 are runners are arranged at opposite ends of the housing 31. Front arc runner 33 has a plurality of spaced apertures 34 disposed along its length. The function performed by apertures 34 will be more fully described in connection with the operation of the arc chute. Front runner 33 is connected to front runner arc horn 35.

- Conductive strap 36 serves to connect the lower end of arc horn 35 to conductive block 23.

Rear arc runner 32 is connected .at its lower end to rear are born 37. A face wound blow-out coil (not shown) is contained in the front face of arc chute housing 31 and is secured by a suitable means to arc chute housing 31. One terminal (not shown) of the blow-out coil contained in housing 31 is electrically connected to conductive strap 39. The other terminal of the face wound blow-out coil is electrically connected to conductive rod 40, the opposite end of rod 40 being connected to conductive head 15.

My novel structure may also be used with the blowout coil structure shown in FIGURE 2 where blow-out coils 38 -38 are mounted on opposite sides of arc chute housing 31. Blow-out coils 3838' surround iron core 38a which core surrounds the outer perimeter of arc chute housing 31. One terminal of blow-out coil 38 is electrically connected to conductive strap 39 at point 55. The other terminal of blow-out coil 38 is electrically connected to conductive rod 40 at point'56. One terminal of blow-out coil 38 is electrically connected to conductive strap 39 at point 55 while the other terminal of blow-out coil 38 is electrically connected to conductive strap 57 at point 56. Conductive strap 57 is connected to rear arc born 37 to complete the electrical circuit for blow-out coils 3838'.

A jump gap 42 is positioned at the lower end of arc horn 37. Jump gap 42 is secured between plates 43, the upper end of plates 43 being mounted to rear arc horn 37 by bolt 44. A portion of front plate 43 has been cut away to show the position of jump gap 42. Guide plates41 are mounted above .and below jump gap 42. The guide plates are secured at one end by bolts 44 and 45 while the opposite ends are secured by bolt 46.

A plurality of arc plates 47 are mounted a spaced distance apart between the front 33 and rear 32 are runners. Only four plates are shown in FIGURE 1 for reasons of clarity, but it should be understood the arc plates 47 occupy the entire-space between arc runners 32 and 33. Each arc plate 47 is tapered at its lower end 48. The are plates 47 are arranged in a staggered fashion to form a V-shaped passage which extends between the arc runners 32 and 33. The lower edges of alternate arcplates' 47 which taper to the rear of the arc chute rest on horizontal ledge 49 which is secured to the arc chute housing 31. A similar ledge 49a is provided on the opposite side of arc chute housing 31 for the remaining arc plates whose lower edges taper toward the front of the arc chute housing 31. To prevent horizontal movement of the arc plates 47 in the arc chute, vertical slots may be provided in the side walls of arc chute housing 31 or spacers may be provided for rigid positioning of the arc plates 47. Some other ways ofmounting arc plates 47 are set forth in US. Patent No. 2,761,- 934 entitled High Voltage Circuit Breakers issued September 4, 1956 to J. D. Wood et al. and assigned to the same assignee as the instant application: US. Patent No. 2,941,060 entitled Arc Extinguishing Means for High Voltage Circuit Breakers, issued June 14, 1960 to A. S. Caswell and assigned to the same assignee as the instant invention, and US. Patent No. 2,905,792 entitled Arc Chute Construction Having Resilient Spacing Means, issued'September 22, 1959 to A. S. Caswell and assigned to the same assignee as the instant invention. All three of the above patents describe arc plate mounting means suitable for use in the arc chute of my invention, and they are hereby incorporated into the instant application.

The operation of the arc chute is as follows in connection with FIGURE 2:

Upon the occurrence of an overload or short-circuit condition, push rod 26 moves in the direction of arrow 50, causing bridge 20 to rotate clockwise about pivot 22. Contacts 16 and 13 separate first transferring all the current to arcing contacts 17 and 19. As bridge 20 moves still further in the clockwise position (shown by the dotted line 2G)'arcing contacts 17 and 19 become disengaged causing an arc B to be' drawn therebetween. The ionized gases formed by the tripping operation are substantially heated by arc B and begin to rise rapidly in the direction of the arc chute 30. The spacing between the arc plates 47 will not permit the ionized gases to pass rapidly between the arc plates. A large back pressure builds up, causing the ionized gases to collect in the region below the arc plates 47 as shown by the shaded area D.

As arc B moves upward, jump gap 42 causes the end of are E impinging on contact 17 to be transferred to rear arc horn 37 while the further clockwise movement of bridge 20 causes the'end of arc B impinging on contact 19 to be transferred'to' front are horn 35. The are is now in position C.

The current path through the circuit breaker now extends from lower terminal 14, conductive block 23, conductive strap 36, front are born 35, are C, rear arc horn 37, conductive strap 57, the blow-out coil 38', conductive strap 39, blow-out coil 38, conductive rod 40, conductive head 15 and upper terminal 13.

The blow-out coils 38- 38 are now energized, causing the are C to be urged rapidly upward through arc plates 47. During this time the ionized gases gathering the shaded area D start to dilfuse through jump gap Since the blow-out coils 38 and 38' are connected between the upper terminal 55 of the blow-out coil and arcing contact 17, the'voltage developed across the blow-out coil also exists between arc horn 37 and arcing contact 17 as shown by the voltage E. The ionized gases spanning the voltage B will therefore cause an arc to be drawn across jump gap 42 which will deenergize the blow-out coil which will resultin a termination of the rapid movement of are C through the arc chute 30.

To prevent arcing or fiashover across jump gap 42, a passage 50 is provided between rear arc runner 32. and are chute housing 31. Guide plates 41, formed of an insulating material, guide the ionized gases which are diffused through jump gap 42 towards the lower opening 51 of passage 50. The dimensions of passage 5a are such as to permit the ionized gases .to move at a very rapid rate through passage 50 and out of the top of the arc chute by means of the upper opening 52.

As the arc moves upward through arc chute 30 it is drawn between arc runners 32 and 33. In this position the are, now shown at F, extends through the \'-shaped arch formed by are plates 47. The arc voltage E developed by the arc F is also impressed across the points G. The ionized gases collected in the shaded area D will induce a flashover between points G.

It is noted, however, that the width of arc horn 37 is substantially less than the width of rear arc runner 32. This permits the ionized gases collecting in the shaded area D to move around arc horn 37 towards the lower opening 51 of passage 50. The dimensions of arc horn 37 are such that it offers almost no resistance to the gases moving towards the opening 51 of passage 50. Upper guide plate 41 acts to guide the gases moving towards lower opening 51 thus forcing the gases in the region of upper guide plate rapidly in the direction of lower opening 51. A V-shaped slot (see FIGURE 1) is provided in rear arc runner 32 to present a larger opening to the gases entering passage 50. The slot 60 likewise contributes to the more rapid removal of the ionized gases.

A second passage 51 formed by front arc runner 33 and arc chute housing 31 may also be provided in the arc chute. This will permit the rate of removal of the ionized gases to be doubled, thus preventing a flashover to occur across points H as well as the above mentioned fiashover points E and G. The operation of passage 51 is the same as that of pas-sage 50.

To further facilitate removal of ionized gases a plurality of spaced apertures 34 (see FIGURE 1) are arranged along front are runner 33. The rapidly rising gases in passage 51 create a slight vacuum in the space to the left of front are runner 33 causing ionized gases in this space to pass through apertures 34. The ionized gases drawn through the apertures are then urged upward to the top of arc chute 30. Rear arc runner 32 may also be provided with apertures.

The length of passage 50 is such that at the time the ionized gases leave the opening 52 of passage 50, they are sufficiently cooled and deionized. The absence of deionized gases above the arc chute prevents the possibility of a flashover between arc runners 32 and 33 above the arc plates 47.

It can be seen from the foregoing description that I have provided a circuit breaker having a novel are chute in which ionized gases from during the tripping operation are rapidly removed from the region of the breaker contacts to prevent restrikes within the breaker and in which the gases are deionized and cooled during their removal to prevent a flashover from occurring between the arc runners above the arc chute.

In the foregoing, I have described my invention only in connection with the preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein, but only by the appending claims.

I claim:

1.'In combination, a pair of cooperating contacts, an arc chute adjacent said contacts for extinguishing an are drawn between said contacts upon separation thereof, said are chute comprising a front and a rear arc runner positioned at opposite ends of said are chute, a plurality of arc plates positioned a spaced distance apart in said arc chute between said front and rear runners, each of said are runners having an upper and a lower portion, said upper portion being mounted vertically in said are chute, said lower portion sloping inward from said upper portion towards the center of said are chute, said upper portion being substantially as wide as said are chute, the width of said lower portion being substantially less than the width of said upper portion, the upper portion of each of said arc runners being spaced a predetermined distance from the ends of said are chute substantially greater than the distance between adjacent arc plates and each forming a vertical passage between said rear arc runner and said are chute, said vertical passages forming escape paths to permit ionized gases in the region of said contacts generated by said are to move rapidly through said passages to the top of said are chute, said passages causing the gases moving therethrough to be cooled and deionized; guide means substantially in alignment with said rear arc runner lower portion positioned between said are chute and said cooperating contacts and adapted to direct ionized gases generated during circuit interruption directly to the lower edge of said rear are runner to prevent accumulation of gases beneath said arc plates in the immediate region of said cooperating contacts.

2. In combination, a pair of cooperating contacts, an arc chute positioned to receive an electric current arc formed between said contacts upon separation thereof, said are chute having a pair of arc runners positioned at opposite ends of said are chute, a plurality of arc plates placed a spaced distance apart interposed between said are runners, one of said are runners having an upper and a lower portion, said upper portion being aligned vertically a spaced distance from the end of said arc chute to form a passage for exiting gases, said lower portion sloping inward from the bottom of said upper portion towards the center of said arc chute, the width of said lower portion being substantially less than the width or" said upperportion to provide a path by which ionized gases generated by said are move unimpeded from the region of said contacts to the lower opening of said passage, and a guiding plate connected to said lower portion for guiding said ionized gases towards said passage and preventing the accumulation of gases in the region adjacent said cooperating contacts and beneath said are plates, said guiding plate being aligned at an angle substantially the same as the angle of alignment of said rear arc runner lower portion.

3. In combination, a pair of cooperating contacts, an arc chute positioned to receive an electric current are formed between said contacts upon separation thereof, a pair of arc runners positioned at opposite ends of said are chute, a plurality of spaced arc plates inserted in said are chute between said are runners, one of said are runners having an upper and a lower portion, said upper portion being aligned vertically in said are chute a spaced distance from the end of said are chute to form a passage for exiting gases, the lower end of said upper portion having a V-shaped slot, said lower portion sloping inward from the bottom of said upward portion towards the center .of said are chute, the width of said lower portion being substantially smaller than the width of said upper portion, the upper end of said lower portion being joined with said upper portion above the apex of said V-shaped slot, a guiding plate substantially in alignment with said rear arc runner lower portion connected to said lower portion for guiding said ionized gases from the region of said contacts to the lower opening of said passage, and for preventing the accumulation of gases in the region beneath the arc plates and adjacent the cooperating contacts, said lower portion and said V-shaped slot being adapted to permit ionized gases formed by said are to move unimpeded from the region of said contacts to the lower opening of said passage, and said passage being adapted to deionize and cool the gases moving therethrough.

4. In combination, a pair of cooperating contacts, an arc chute positioned to receive an electric current are formed between said contacts upon separation thereof, first and second arc runners positioned at opposite ends of said are chute, a plurality of spaced arc plates inserted in said are chute between said are runners, said first arc runner being aligned vertically in said are chute a spaced distance from the end of said arc chute forming a passage for exiting gases, first and second guide plates substantially in alignment with said rear arc runner lower portion connected to the lower end of said first arc runner, a jump gap inserted between said guide plates, said guide plates being adapted to guide ionized gases formed in the region of said contacts rapidly through said jump gap into the lower opening of said passage and for preventing the accumulation of gases in the region beneath the arc plates and adjacent the cooperating contacts wherein said gases are deionized and cooled before exiting from said are chute.

5. In combination, a pair of cooperating contacts, an arc chute arranged to receive an electric current are drawn between said contacts upon separation thereof, first and second arc runners positioned at opposite ends of said are chute, a plurality of spaced arc plates inserted between said arc runners in said are chute, said first arc runner having an upper and a lower portion, said upper portion being vertically aligned in said are chute a spaced distance from the end of said are chute to form a passage for exiting gases, the lower end of said upper portion having a V-shaped slot, said lower portion sloping inward from a 'point above said V-shaped slot towards the center of said arc chute, the width of said lower portion being substantially less than the width of said upper portion, said lower portion and said if-shaped slot cooperating topermit ionized gases formed by said are to move unimpeded from the region of said contacts to the lower opening of said passage, a pair of guide plates substantially in alignment with said rear arc runner lower portion connected to the lower portion of said first arc runner, a jump gap inserted between said guide plates, said guide plates acting to guide ionized gases in the region of said are through said jump gap to the lower opening, and for preventing the accumulation of gases in the region beneath the arc plates and adjacent the cooperating contacts, said passage preventing an are from being drawn across said jump gap.

6. In combination, a pair of cooperating contacts, an arc chute arranged to receive an electric current are drawn between said contacts upon separation thereof, first and second arc runners positioned at opposite ends of said are chute, a plurality of spaced are plates inserted between said are runners in said are chute, said first arc runner having an upper and a lower portion, said upper portion being vertically aligned in said are chute a spaced distance from the end of said are chute to form a passage for exiting gases, said upper portion having a plurality of spaced apertures for aiding the upward movement of said exiting gases, the lower end of said upper portion having a V-shaped slot, said lower portion sloping in-' ward from a point above said V-shaped slot towards the center of said are chute, the width of said lower portion being substantially less than the width of said upper portion, said lower portion and said V-shaped slot cooperating to permit ionized gases formed by said are to move unimpeded from the region of said contacts to the lower opening of said passage, a pair of guide plates substantially in alignment with said rear arc runner lower portion connected to the lower portion of said first are runner, a jump gap inserted between said guide plates, said guide plates acting to guide ionized gases in the region of said are through said jump gap to the lower opening, and for preventing the accumulation of gases in the region beneath the arc plates and adjacent the cooperating contacts, said passage preventing an are from being drawn across said jump gap.

7. In combination, a pair of cooperating contacts, an arc chute arranged to receive an electric current are drawn between said contacts upon separation thereof, first and second arc runners positioned at opposite ends of'said arc chute, a plurality of spaced arc plates inserted between said are runners in said are chute, said first arc runner having an upper and a lower portion, said upper portion being vertically aligned in said are chute a spaced distance from the end of said are chute to form a passage for exiting gases, the upper portions of said are runners having a plurality'of spaced apertures for aiding the upward movement of said exiting gases, the lower end of said upper portion having a V-shaped slot, said lower portion sloping inward from a point above said V-shaped slot towards the center of said are chute, the width of said lower portion being substantially less than the width of said upper portion, said lower portion and said V-shaped slot cooperating to permit ionized gases formed by said are to move unimpeded from the region of said contacts to the lower opening of said passage, 21 pair of guide plates substantially in alignment with said rear arc runner lower portion connected to the lower portion of said first arc runner, a jump gap inserted between said guide plates, said guide plates acting to guide ionized gases in the region of said are through said jump gap to the lower opening, and for preventing the accumulation of gases in the region beneath the arc plates and adjacent the cooperating contacts, said passage preventing an are from being drawn across said jump gap.

References Cited in the file of this patent UNITED STATES PATENTS 2,243,040 Ludwig et al. May 20, 1941 2,276,859 Nau Mar. 17, 1942 2,632,075 Rawlins Mar. 17, 1953 2,648,743 Taylor Aug. 11, 1953 2,777,036 Frink et al. Jan. 8, 1957 2,831,946 Wood Apr. 22, 1958 2,904,659 Boehne Sept. 15, 1959 2,920,170 CasWcll Jan. 5, 1960 

1. IN COMBINATION, A PAIR OF COOPERATING CONTACTS, AN ARC CHUTE ADJACENT SAID CONTACTS FOR EXTINGUISHING AN ARC DRAWN BETWEEN SAID CONTACTS UPON SEPARATION THEREOF, SAID ARC CHUTE COMPRISING A FRONT AND A REAR ARC RUNNER POSITIONED AT OPPOSITE ENDS OF SAID ARC CHUTE, A PLURALITY OF ARC PLATES POSITIONED A SPACED DISTANCE APART IN SAID ARC CHUTE BETWEEN SAID FRONT AND REAR RUNNERS, EACH OF SAID ARC RUNNERS HAVING AN UPPER AND A LOWER PORTION, SAID UPPER PORTION BEING MOUNTED VERTICALLY IN SAID ARC CHUTE, SAID LOWER PORTION SLOPING INWARD FROM SAID UPPER PORTION TOWARDS THE CENTER OF SAID ARC CHUTE, SAID UPPER PORTION BEING SUBSTANTIALLY AS WIDE AS SAID ARC CHUTE, THE WIDTH OF SAID LOWER PORTION BEING SUBSTANTIALLY LESS THAN THE WIDTH OF SAID UPPER PORTION, THE UPPER PORTION OF EACH OF SAID ARC RUNNERS BEING SPACED A PREDETERMINED DISTANCE FROM THE ENDS OF SAID ARC CHUTE SUBSTANTIALLY GREATER THAN THE DISTANCE BETWEEN ADJACENT ARC PLATES AND EACH FORMING A VERTICAL PASSAGE BETWEEN SAID REAR ARC RUNNER AND SAID ARC CHUTE, SAID VERTICAL PASSAGES FORMING ESCAPE PATHS TO PERMIT IONIZED GASES IN THE REGION OF SAID CONTACTS GENERATED BY SAID ARC TO MOVE RAPIDLY THROUGH SAID PASSAGES TO THE TOP OF SAID ARC CHUTE, SAID PASSAGES CAUSING THE GASES MOVING THERETHROUGH TO BE COOLED AND DEIONIZED; GUIDE MEANS SUBSTANTIALLY IN ALIGNMENT WITH SAID REAR ARC RUNNER LOWER PORTION POSITIONED BETWEEN SAID ARC CHUTE AND SAID COOPERATING CONTACTS AND ADAPTED TO DIRECT IONIZED GASES GENERATED DURING CIRCUIT INTERRUPTION DIRECTLY TO THE LOWER EDGE OF SAID REAR ARC RUNNER TO PREVENT ACCUMULATION OF GASES BENEATH SAID ARC PLATES IN THE IMMEDIATE REGION OF SAID COOPERATING CONTACTS. 